On Thu, Jul 17, 2014 at 5:25 PM, Marcin Gibuła <m.gib...@beyond.pl> wrote: >>> 2.1-rc2 behaves exactly the same. >>> >>> Interestingly enough, reseting guest system causes I/O to work again. So >>> it's not qemu that hangs on IO, rather it fails to notify guest about >>> completed operations that were issued during migration. >>> >>> And its somehow caused by calling cpu_synchronize_all_states() inside >>> kvmclock_vm_state_change(). >>> >>> >>> >>> As for testing with cache=writeback, I'll try to setup some iscsi to test >>> it. >> >> >> Awesome, thanks! AFAIK you`ll not be able to use write cache with >> iscsi for migration. VM which had a reset before hangs always when >> freshly launched have a chance to be migrated successfully. And yes, >> it looks like lower layer forgetting to notify driver about some >> operations at a glance. > > > Andrey, > > could you try attached patch? It's an incredibly ugly workaround that calls > cpu_synchronize_all_states() in a way that bypasses lazy execution logic. > > But it works for me. If that works for you as well, its somehow related to > lazy execution of cpu_synchronize_all_states. > > -- > mg
Yes, it working well with writeback cache too.
